Liquid ejecting head and liquid ejecting apparatus

Abstract

The present disclosure provides a liquid ejecting head and a liquid ejecting apparatus. The liquid ejecting head includes a driving element and a nozzle. A shape of a cross section at a specific position in an ejecting direction within the nozzle, i.e., a first position, is set to a first outer shape. A direction orthogonal to the ejecting direction and a long side direction of the first outer shape is set to a first direction. A direction orthogonal to both the ejecting direction and the first direction is set to a second direction. A straight line passing through a center of the first direction of the first outer shape and extending in the second direction is set to a first center line. A first width, which is the largest in the second direction, in a portion of the first outer shape on one side of the first center line in the first direction is located at a specific position in the first direction, i.e., a third position. A second width, which is the largest in the second direction, in a portion of the first outer shape on the other side of the first center line in the first direction is located at a specific position in the first direction, i.e., a fourth position. A first distance between the third position and the fourth position in the first direction is larger than the first width and larger than the second width.

Description

Technical Field

[0001] This disclosure relates to a liquid jet head and a liquid jetting device. Background Technology

[0002] Patent Document 1 discloses a liquid injection head with a two-stage nozzle structure and a nozzle shape near the opening end formed by two arcs partially overlapping each other. In this liquid injection head, liquid is less likely to stagnate in the nozzle, thus reducing the possibility of poor injection due to liquid stagnation.

[0003] However, the inventors of this disclosure have discovered a problem with the nozzle shapes described in the prior art: droplets are ejected independently from the two arcs, potentially causing the droplets to remain in a broken state and adhere to the medium. Therefore, a technique is desired that reduces the likelihood of droplets remaining in a broken state and falling onto the medium.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2021-66159 Summary of the Invention

[0005] (1) According to a first aspect of this disclosure, a liquid injection head is provided, comprising: a drive element that generates pressure for injecting liquid; and a nozzle for injecting liquid in an injection direction by utilizing the pressure generated by the drive element. A specific position in the injection direction within the nozzle is designated as a first position. The specific position in the injection direction within the nozzle is designated as the first position, the shape of the cross section at the first position of the nozzle in the direction perpendicular to the injection direction is designated as a first shape, a direction orthogonal to the injection direction and being the direction of the long side of the first shape is designated as a first direction, a direction orthogonal to both the injection direction and the first direction is designated as a second direction, and a straight line passing through the center of the first shape in the first direction and extending in the second direction is designated as a first centerline. A first width, which is the largest in the second direction among the portions of the first shape relative to the first centerline on the side of the first direction, is located at a third position, which is the specific position in the first direction; a second width, which is the largest in the second direction among the portions of the first shape relative to the first centerline on the other side of the first direction, is located at a fourth position, which is the specific position in the first direction; and a first distance between the third position and the fourth position in the first direction is greater than the first width and greater than the second width.

[0006] (2) According to a second aspect of this disclosure, a liquid injection head is provided, comprising: a drive element that generates pressure for injecting liquid; and a nozzle for injecting liquid in a injection direction by utilizing the pressure generated by the drive element. A specific position in the injection direction within the nozzle is designated as a first position, and the shape of a cross-section at the first position of the nozzle in a direction perpendicular to the injection direction is designated as a first shape. The first shape includes a first arc, a second arc, and a connecting portion connecting the first arc and the second arc. A second distance between the center of a first imaginary circle (which is a perfect circle or ellipse and is part of the circumference of the first arc) and the center of a second imaginary circle (which is a perfect circle or ellipse and is part of the circumference of the second arc) is greater than the diameter of the first imaginary circle measured along a first direction in which the first arc and the second arc are parallel, and the width of the connecting portion measured along a second direction orthogonal to both the first direction and the injection direction is less than the diameter of the first imaginary circle measured along the second direction. Attached Figure Description

[0007] Figure 1 This is an explanatory diagram showing the structure of the liquid injection device in the embodiment.

[0008] Figure 2 This is a bottom view of the liquid injection head.

[0009] Figure 3 for Figure 2 Sectional view of section III-III.

[0010] Figure 4 A diagram showing the cross-sectional shape of the nozzle in the first embodiment.

[0011] Figure 5 To indicate Figure 4 A diagram of the nozzle shape of the first embodiment viewed from the VV direction.

[0012] Figure 6 This is a diagram showing the nozzle shape of the second embodiment.

[0013] Figure 7 This is a diagram showing the nozzle shape of the third embodiment.

[0014] Figure 8 This is a diagram showing the nozzle shape of the fourth embodiment.

[0015] Figure 9 This diagram illustrates the nozzle shape according to the fifth embodiment.

[0016] Figure 10 A diagram showing the cross-sectional shape of the nozzle according to the sixth embodiment.

[0017] Figure 11 To indicate Figure 10 A diagram showing the nozzle shape of the sixth embodiment viewed from the XI-XI direction.

[0018] Figure 12 This diagram illustrates the nozzle shape according to the seventh embodiment.

[0019] Figure 13 This is a diagram showing the nozzle shape of the eighth embodiment. Detailed Implementation

[0020] A. First Implementation Method

[0021] Figure 1 This is an explanatory diagram showing the structure of the liquid jetting apparatus 400 in the embodiment. The liquid jetting apparatus 400 is an inkjet printing apparatus that jets ink, as an example of a liquid, towards a medium PM. The composition of the ink is not particularly limited; for example, it can be a water-based ink obtained by dissolving color materials such as dyes or pigments in an aqueous solvent, a solvent-based ink obtained by dissolving color materials in an organic solvent, or an ultraviolet-curable ink. Furthermore, the liquid jetting apparatus 400 can also jet coatings in liquid form instead of ink. A liquid reservoir 420 for storing ink can be installed in the liquid jetting apparatus 400. The liquid jetting apparatus 400 performs printing by jetting the ink in the liquid reservoir 420 toward the medium PM. The liquid jetting apparatus 400 includes a liquid jetting head 100, a moving mechanism 430, a conveying mechanism 440, and a control unit 450.

[0022] The liquid jet head 100 has multiple nozzles and jets liquid ink supplied from the liquid reservoir 420 from these nozzles. Specific examples of the liquid reservoir 420 include containers such as a detachable box from the liquid jet device 100, a bag-shaped ink pouch formed of a flexible film, and an ink can for refilling ink. The ink jetted from the nozzles lands on the medium PM. The medium PM is typically printing paper. However, the medium M is not limited to printing paper; for example, it can be any printing material such as resin film or fabric.

[0023] The moving mechanism 430 includes an annular belt 432 and a carriage 434 fixed on the belt 432. The carriage 434 holds the liquid injection head 100. The moving mechanism 430 can reciprocate the liquid injection head 100 in the X direction by rotating the annular belt 432 in both directions.

[0024] The conveying mechanism 440 conveys the medium PM along the Y direction during the intervals between multiple movements of the liquid jet head 100 implemented by the moving mechanism 430. The Y direction is a direction orthogonal to the X direction. In this embodiment, the X and Y directions are horizontal. The Z direction is a direction perpendicular to both the X and Y directions and is vertically downward. The liquid jet head 100 jets ink along the Z direction during the period of being conveyed along the X direction. The Z direction is also referred to as the "jet direction Z". Furthermore, in the following description, the top side of the arrow indicating the X direction in the figure is called the +X side, and the base side is called the -X side; the top side of the arrow indicating the Y direction in the figure is called the +Y side, and the base side is called the -Y side; and the top side of the arrow indicating the Z direction in the figure is called the +Z side, and the base side is called the -Z side.

[0025] Control unit 450 controls the ejection action of ink from liquid ejector head 100. Control unit 450 controls conveying mechanism 440, moving mechanism 430 and liquid ejector head 100 so that an image is formed on medium PM.

[0026] Figure 2 This is a bottom view of the liquid injection head 100. The liquid injection head 100 has a plurality of nozzles 200. The plurality of nozzles 200 are formed through a nozzle plate 240 arranged parallel to the XY plane and are arranged in a straight line along the Y direction.

[0027] Figure 3 for Figure 2The image shows a cross-sectional view at section III-III. The liquid jet head 100 has a first common liquid chamber 110 for supplying ink, a second common liquid chamber 120 for discharging ink, and a connecting channel 130 connecting the first common liquid chamber 110 and the second common liquid chamber 120. The connecting channel 130 has a first pressure chamber 131 and a second pressure chamber 132, and a connecting channel 134 connecting the two pressure chambers 131 and 132. The first common liquid chamber 110 and the second common liquid chamber 120 are shared by multiple nozzles 200, and the connecting channel 130 is independently provided for each nozzle 200. The lower portions of the common liquid chambers 110 and 120 and the connecting channel 130 are mainly formed by a connecting plate 140. Alternatively, the connecting plate 140 can also be constructed by stacking multiple substrates. A channel substrate 160 is provided on the upper surface of the connecting plate 140. A nozzle plate 240 is provided on the lower surface of the connecting plate 140. Furthermore, the lower ends of the first common liquid chamber 110 and the second common liquid chamber 120 are sealed by a flexible sealing membrane 150. Openings at the upper ends of the first common liquid chamber 110 and the second common liquid chamber 120 are respectively connected to an external circulation channel 170. A circulation mechanism 180, including a pump, is provided on the circulation channel 170. Ink is supplied from the circulation channel 170 to the first common liquid chamber 110, and after a portion of the ink is ejected from the nozzle 200 to the outside, it is discharged from the second common liquid chamber 120 to the circulation channel 170. The liquid reservoir 420 can either be configured as part of the circulation mechanism 180 by being located midway through the circulation channel 170, or it can be configured to be independent of the circulation mechanism 180 and supplied with liquid by connecting to the circulation channel 170. However, the circulation mechanism 180 can be omitted.

[0028] The connecting channel 134 extends along the X direction, and a nozzle 200 is disposed in the middle of the connecting channel 134. Although the connecting channel 134 in this embodiment extends in the X direction with the X direction as its long side, the connecting channel 134 may also extend in a direction intersecting the X direction as its long side. A first driving element 301 is disposed on the first pressure chamber 131, and a second driving element 302 is disposed on the second pressure chamber 132. The first driving element 301 and the second driving element 302 are, for example, constructed of piezoelectric elements. The piezoelectric element is, for example, constructed of a piezoelectric layer and two electrodes disposed in a manner that sandwiches the piezoelectric layer. A vibrating plate 310 is disposed between the first driving element 301 and the first pressure chamber 131, and between the second driving element 302 and the second pressure chamber 132. When the driving elements 301 and 302, which are piezoelectric elements, vibrate, their vibration is transmitted to the pressure chambers 131 and 132, thereby generating pressure waves in the pressure chambers 131 and 132. Ink is ejected from nozzle 200 by pressure generated by drive elements 301 and 302. When ejecting ink from nozzle 200, it is preferable that the first drive element 301 and the second drive element 302 are driven simultaneously in the same phase. Alternatively, instead of piezoelectric elements, heating elements that heat the ink within pressure chambers 131 and 132 may be used as drive elements.

[0029] Although Figure 3 In the example, two pressure chambers 131 and 132 are provided for one nozzle, but there may be only one pressure chamber, or there may be more than three. In any case, the drive element is configured to correspond to each pressure chamber.

[0030] Figure 4 This is a magnified view showing the cross-sectional shape of the nozzle 200 according to the first embodiment. The nozzle 200 has a first portion 210 and a second portion 220 along the Z direction. The first portion 210 is located downstream of the second portion 220 in the jetting direction Z, i.e., closer to the nozzle opening 216. The first portion 210 has a depth L1, and the second portion 220 has a depth L2. Preferably, the shape of the first portion 210 in the cross-section perpendicular to the jetting direction Z is fixed regardless of the position Pz1 of the jetting direction Z. Furthermore, it is preferable that the shape of the second portion 220 in the cross-section perpendicular to the jetting direction Z is also fixed regardless of the position Pz2 of the jetting direction Z. Preferably, the depth L2 of the second portion 220 is greater than the depth L1 of the first portion 210. If L1 < L2, it has the advantage of easily preventing the ingress of air bubbles after ink jetting. In the following, the shape of the first portion 210 will be referred to simply as "first shape 210", and the shape of the second portion 220 will be referred to simply as "second shape 220".

[0031] Figure 5 To indicate Figure 4 A diagram showing the nozzle shape of the first embodiment viewed from the VV direction. Here, for ease of illustration, the second outline 220 is depicted with a single-dotted line, and the first imaginary circle VC1 and the second imaginary circle VC2, described later, are depicted with dashed lines. The other diagrams described later are similar.

[0032] The first shape 210 is Figure 4 The first position Pz1 refers to the nozzle shape in a cross-section perpendicular to the spray direction Z at a specific position Pz1 within the nozzle 200 in the spray direction Z. The first shape 210 includes a first arc 211, a second arc 212, and a connecting portion 213 connecting the first arc 211 and the second arc 212. The first shape 210 has a so-called dumbbell shape. That is, the first arc 211 and the second arc 212 are arranged at positions that do not overlap with each other and are connected by a rectangular connecting portion 213. Preferably, the first imaginary circle VC1, in which the first arc 211 is part of a circumference, and the second imaginary circle VC2, in which the second arc 212 is part of a circumference, are either circular or elliptical, and are particularly preferably circular. In this disclosure, "circular" means a circle whose value obtained by dividing the shortest diameter by the longest diameter is 0.9 or more. Furthermore, "circle" is used as a term that includes circular, elliptical, and oblong shapes. Preferably, the first arc 211 and the second arc 212 have congruent shapes, and further preferably, they have shapes that are linearly symmetrical with respect to the center line CL1 of the first outer shape 210. As in this embodiment, the first arc 211 and the second arc 212 are arranged side by side in the X direction, which is the long side direction of the connecting flow channel 134.

[0033] The second exterior shape 220 is, Figure 4 The second position Pz2 refers to the nozzle shape in a cross-section perpendicular to the jet direction Z at a specific position within the nozzle 200 in the jet direction Z. The second shape 220 has a so-called oval (quasi-circular) shape. In this disclosure, "oval shape" is used as a term that includes oblong, elliptical, and ovate shapes. The second shape 220 may also be set to a shape other than an oval shape. However, it is preferable that the second shape 220 is set to be the size that encloses the first shape 210.

[0034] In this embodiment, the connecting portion 213 has a rectangular shape. However, there is no edge corresponding to the connection portion between the connecting portion 213 and the first arc 211, nor is there an edge corresponding to the connection portion between the connecting portion 213 and the second arc 212. Therefore, in Figure 5 In the middle, the connecting part 213 is depicted only by two sides parallel to the X direction.

[0035] Thus, by providing a connecting portion 213 between the first arc 211 and the second arc 212, the possibility of the droplet remaining in a split state and falling onto the medium, which is a problem in the prior art, can be reduced. In the prior art, the nozzle shape near the opening end of the nozzle is designed such that the two arcs partially overlap each other, resulting in the possibility of the droplet splitting into two. This is presumably because the droplets are ejected in opposite directions at the timing of ejection from the nozzle. On the other hand, as can be seen from the results of experiments conducted by the inventors of this disclosure, such as Figure 5 As shown, by separating the first arc 211 and the second arc 212 from each other and providing a connecting portion 213 between them, the possibility of the liquid being sprayed onto the medium PM while maintaining the state of the droplet splitting into multiple parts can be reduced. It is speculated that this is because the capillary force of the liquid present in the connecting portion 213 acts in a way that pulls the liquid in the two arcs 211 and 212 against each other. At this time, the second distance D2 between the center C1 of the first imaginary circle VC1 and the center C2 of the second imaginary circle VC2, in other words, the distance D2 between the centers of the first arc 211 and the second arc 212, becomes greater than the diameters R1 and R2 of the first arc 211 and the second arc 212, in other words, the diameters R1 and R2 of the first imaginary circle VC1 and the second imaginary circle VC2. Since the first imaginary circle VC1 and the second imaginary circle VC2 are both perfect circles in this embodiment, the diameter R1 of the first imaginary circle VC1 measured along the first direction Dr1 (described later) is equal to the diameter R1 of the first imaginary circle VC1 measured along the second direction Dr2 (described later). The same applies to the second imaginary circle VC2.

[0036] Preferably, the diameters R1 and R2 of the first arc 211 and the second arc 212 are, for example, 20 μm or more and 30 μm or less. To reduce the possibility of droplets falling onto the medium PM in a split state, it is preferable that the value R1 / D2, obtained by dividing the diameter R1 of the first arc 211 by the second distance D2, which is the distance between the centers of the two arcs 211 and 212, is 0.775 or more. Similarly, it is preferable that the value R2 / D2, obtained by dividing the diameter R2 of the second arc 212 by the second distance D2, which is the distance between the centers of the two arcs 211 and 212, is also 0.775 or more.

[0037] Preferably, Figure 4 The depth L1 of the first portion 210 shown is, for example, set to be 10 μm or more and 40 μm or less. In order to reduce the possibility of droplets falling onto the medium PM in a split state, it is preferable that the value L1 / L2 obtained by dividing the depth L1 of the first portion 210 by the depth L2 of the second portion 220 is set to be 0.2 or more and 1.2 or less.

[0038] The viscosity of the ink is preferably 20 mPa·s or less at 25°C, and more preferably 3 mPa·s or more. Alternatively, the viscosity of the ink may also be 110 mPa·s or less at 25°C. Furthermore, the surface tension of the ink is preferably 20 mN / m or more and 40 mN / m or less at 25°C. Using inks with these properties further enhances the effect of reducing the likelihood of the liquid being sprayed onto the media PM in a fragmented state.

[0039] exist Figure 4 as well as Figure 5 In the diagram, the shape of nozzle 200 is indicated by symbols to show the following orientation or position and dimensions.

[0040] Directions Dr1, Dr2

[0041] The first direction Dr1 is the direction of the long side of the first shape 210. The second direction Dr2 is a direction orthogonal to both the jet direction Z and the first direction Dr1. In this embodiment, the first direction Dr1 is parallel to the X direction, and the second direction Dr2 is parallel to the Y direction.

[0042] Center C, Cx, Cy

[0043] Center C is the center of the first shape 210. Cx is the X-direction position of center C, and Cy is the Y-direction position of center C.

[0044] Center C1, C2

[0045] The first center C1 is the center of the first arc 211. The second center C2 is the center of the second arc 212. Alternatively, the first center C1 can be considered the center of a first imaginary circle VC1, in which the first arc 211 is part of a circle. Similarly, the second center C2 can be considered the center of a second imaginary circle VC2, in which the second arc 212 is part of a circle. These imaginary circles VC1 and VC2 are preferably perfect circles or ellipses, and are particularly preferably perfect circles.

[0046] Center lines CL1, CL2

[0047] The first centerline CL1 is a straight line that passes through the center position Cx in the first direction Dr1 of the first shape 210 and extends in the second direction Dr2. The second centerline CL2 is a straight line that passes through the center position Cy in the second direction Dr2 of the first shape 210 and extends in the first direction Dr1. In this embodiment, the first centerline CL1 is parallel to the Y direction, and the second centerline CL2 is parallel to the X direction.

[0048] Positions P1 to P10

[0049] like Figure 4As shown, the first position Pz1 is a specific position in the spray direction Z within the nozzle 200, and is the position of the portion of the nozzle 200 whose cross-section has the first shape 210. Alternatively, the first position Pz1 can also be the top of the nozzle 200 on the spray direction Z side, i.e., the position where the nozzle opening 216 is formed.

[0050] like Figure 4 As shown, the second position Pz2 is a specific position within the nozzle 200 upstream of the first position Pz1 in the jet direction Z, and is the position of the portion of the nozzle 200 whose cross-section has the second shape 220.

[0051] like Figure 5 As shown, the third position P3 is a specific position where the width of the first shape 210, measured along the second direction Dr2, is the largest in the portion of the first shape 210 relative to the first center line CL1 on the side of the first direction Dr1, i.e., the -X side. In this embodiment, at the third position P3, the width W1 of the first arc 211 in the second direction Dr2 becomes the maximum value.

[0052] The fourth position P4 is a specific position in which the width of the first shape 210, measured along the second direction Dr2, is the largest on the +X side of the portion of the first shape 210 relative to the first center line CL1 and on the other side of the first direction Dr1. In this embodiment, at the fourth position P4, the width W2 of the second arc 212 in the second direction Dr2 reaches its maximum value.

[0053] The fifth position P5 is a specific position between the first centerline CL1 and the third position P3. The width of the first shape 210 at the fifth position P5 in the second direction Dr2 is set as the fifth width W5.

[0054] The sixth position P6 is a specific position between the first centerline CL1 and the fourth position P4. The width of the first shape 210 at the sixth position P6 in the second direction Dr2 is set as the sixth width W6.

[0055] The seventh position P7 is a specific position between the first center line CL1 and the third position P3 on the first direction Dr1. Furthermore, the seventh position P7 is set to a position within the range of the connecting portion 213 on the first direction Dr1, that is, the position between the ninth position P9 (described later) and the first center line CL1. In this embodiment, the seventh position P7 may also be set to the same position as the ninth position P9.

[0056] The eighth position P8 is a specific position between the first centerline CL1 and the fourth position P4 on the first direction Dr1. Furthermore, the eighth position P8 is set to a position within the range of the connecting portion 213 on the first direction Dr1, i.e., the position between the tenth position P10 (described later) and the first centerline CL1. In this embodiment, the eighth position P8 may also be set to the same position as the tenth position P10. The width of the first shape 210 on the second direction Dr2 at any position from the seventh position P7 to the eighth position P8 is set to the fourth width W4. In this embodiment, the fourth width W4 is approximately fixed throughout the entire range of the connecting portion 213 on the first direction Dr1. Here, "approximately fixed" means within a range of ±10% of the average value.

[0057] The ninth position P9 is a specific location between the first centerline CL1 on the first direction Dr1 and the third position P3. Furthermore, the ninth position P9 is located at the connection point between the first arc 211 and the connecting portion 213. In this embodiment, the distance r1 between the first outer shape 210 and the first center C1 is approximately fixed on the side of the first outer shape 210 from the ninth position P9 towards the first direction Dr1, i.e., the -X side. Moreover, this distance r1 is equal to half the radius, i.e., the diameter R1, of the first arc 211.

[0058] The tenth position P10 is a specific location between the first centerline CL1 on the first direction Dr1 and the fourth position P4. Furthermore, the tenth position P10 is located at the connection point between the second arc 212 and the connecting portion 213. In this embodiment, on the +X side of the first outer shape 210, on the side opposite to the first direction Dr1 from the tenth position P10, the distance r2 between the first outer shape 210 and the second center C2 is approximately fixed. Moreover, this distance r2 is equal to half the radius, or diameter R2, of the second arc 212.

[0059] Width W1~W7

[0060] The first width W1 is the maximum width of the first outline 210 at the third position P3 along the second direction Dr2. This first width W1 is the width of the first arc 211. Since the first imaginary circle VC1 in this embodiment is a perfect circle, the first width W1 is consistent with the diameter R1 of the first imaginary circle VC1.

[0061] The second width W2 is the maximum width of the first outline 210 at the fourth position P4 along the second direction Dr2. This second width W2 is also the width of the second arc 212. Since the second imaginary circle VC2 in this embodiment is a perfect circle, the second width W2 is consistent with the diameter R2 of the second imaginary circle VC2.

[0062] The third width W3 is the width of the first outer shape 210 at its center position Cx in the first direction Dr1 along the second direction Dr2. This third width W3 is also the width of the connecting portion 213.

[0063] The fourth width W4 is the width of the first shape 210 in the second direction Dr2 at any position from the seventh position P7 to the eighth position P8. In this embodiment, the fourth width W4 is approximately fixed from the seventh position P7 to the eighth position P8. Specifically, the maximum and minimum values ​​of the fourth width W4 are values ​​within ±10% of the average value of the fourth width W4 from the seventh position P7 to the eighth position P8.

[0064] The fifth width W5 is the width of the first outline 210 at the fifth position P5 along the second direction Dr2. This fifth width W5 is also the width of the first arc 211.

[0065] The sixth width W6 is the width of the first outline 210 at the sixth position P6 in the second direction Dr2. This sixth width W6 is also the width of the second arc 212.

[0066] The seventh width W7 is the entire width of the connecting part 213 in the first direction Dr1, and is equal to the distance from the ninth position P9 to the tenth position P10.

[0067] In the first embodiment, the nozzle 200 has the following shape characteristics.

[0068] Shape characteristics F1

[0069] In the first direction Dr1, the first distance D1 between the third position P3 and the fourth position P4 is greater than the first width W1 and greater than the second width W2. Based on the characteristic F1 of this shape, the distance between the two arcs 211 and 212 can be sufficiently increased, thereby reducing the possibility of liquid being sprayed onto the medium PM in a split state. More specifically, by utilizing the capillary force generated by the connecting portion 213, the first droplet ejected from the first arc 211 and the second droplet ejected from the second arc 212 can be sprayed in a direction approaching each other and merged, thereby suppressing the situation where liquid is sprayed onto the medium PM in a split state. Furthermore, it also has the advantage of reducing droplet flight curvature.

[0070] Shape feature F2

[0071] The third width W3 is smaller than either the first width W1 or the second width W2, and the fifth width W5 and the sixth width W6 are both larger than the third width W3. Based on the characteristics of this shape, the width of the connecting portion 213 in the second direction Dr2 is sufficiently small compared to the arcs 211 and 212, thus further reducing the possibility of droplets falling onto the medium PM in a split state.

[0072] Shape characteristics F3

[0073] The fourth width W4 is approximately fixed at any position from the seventh position P7 to the eighth position P8. "Approximately fixed" here means that the fourth width W4 is within ±10% of its average value. Based on this shape characteristic, the possibility of droplets falling onto the medium PM in a split state can be further reduced.

[0074] Shape characteristics F4

[0075] On the -X side of the first shape 210, starting from the ninth position P9 and along the first direction Dr1, the distance r1 between the first shape 210 and the center C1 is approximately fixed. Similarly, on the +X side of the first shape 210, starting from the tenth position P10 and along the first direction Dr1, the distance r2 between the first shape 210 and the second center C2 is approximately fixed. Here, "approximately fixed" means that the minimum value of distance r1 divided by the maximum value of distance r1 is greater than 0.9. The same applies to distance r2. Based on the characteristics of this shape, the first imaginary circle VC1 and the second imaginary circle VC2, which are respectively set as parts of a circle by the two arcs 211 and 212, are approximately circular. Therefore, the possibility of droplets falling onto the medium PM in a split state can be reduced.

[0076] Shape features F5

[0077] The value W1 / D1, obtained by dividing the first width W1 by the first distance D1 between the third position P3 and the fourth position P4, is 0.775 or higher. Similarly, the value W2 / D1, obtained by dividing the second width W2 by the first distance D1 between the third position P3 and the fourth position P4, is 0.775 or higher. Based on the characteristics of this shape, the possibility of droplet breakage can be further reduced.

[0078] Shape characteristics F6

[0079] The average value of W1 / W4, obtained by dividing the first width W1 by the fourth width W4 from the seventh position P7 to the eighth position P8, is 2 or more. Similarly, the average value of W2 / W4, obtained by dividing the second width W2 by the fourth width W4 from the seventh position P7 to the eighth position P8, is 2 or more. Due to the characteristics of this shape, capillary forces are strongly applied, making it easy for the split liquids to reassemble. Therefore, the possibility of droplets falling onto the medium PM in a split state can be further reduced. The average value of W1 / W4 is more preferably 3 or more, and particularly preferably 4 or more. Similarly, the average value of W2 / W4 is also more preferably 3 or more, and particularly preferably 4 or more.

[0080] Shape characteristics F7

[0081] The second distance D2 between the center C1 of the first imaginary circle VC1, which is part of the circumference of the first arc 211, and the center C2 of the second imaginary circle VC2, which is part of the circumference of the second arc 212, is greater than the diameter R1 of the first imaginary circle VC1 measured along the first direction Dr1. Furthermore, the widths W3 and W4 of the connecting portion 213, measured along the second direction Dr2, are smaller than the diameter R1 of the first imaginary circle VC1 measured along the second direction Dr2. Based on the characteristics of this shape, the second distance D2, which is the distance between the centers of the two arcs 211 and 212, can be sufficiently increased, thereby further reducing the possibility of droplets falling onto the medium PM in a split state. More specifically, by utilizing the capillary force generated by the connecting portion 213, the first droplet ejected from the first arc 211 and the second droplet ejected from the second arc 212 are ejected in a direction approaching each other and merge, thereby suppressing the situation where liquid falls onto the medium PM in a split state. Furthermore, jet bending can be reduced. Furthermore, in this embodiment, the first distance D1 between the third position P3 and the fourth position P4 and the second distance D2 between the center C1 of the first imaginary circle VC1 and the center C2 of the second imaginary circle VC2 are the same.

[0082] Shape features F8

[0083] The diameter R1 of the first imaginary circle VC1, in which the first arc 211 is part of the circumference, and the diameter R2 of the second imaginary circle VC2, in which the second arc 212 is part of the circumference, are the same. Due to the characteristics of this shape, the split-ejected droplets are easily ejected evenly, thus reducing the flight curvature of the droplets.

[0084] Shape characteristics F9

[0085] The length of the first arc 211 is the same as the length of the second arc 212. Due to the characteristics of this shape, the split-ejected droplets are easily ejected evenly, thus reducing the flight curvature of the droplets.

[0086] Shape feature F10

[0087] The first imaginary circle VC1, which is part of the circumference of the first arc 211, and the second imaginary circle VC2, which is part of the circumference of the second arc 212, are both perfect circles. Based on the characteristics of this shape, the possibility of droplets falling onto the medium PM in a split state can be reduced.

[0088] Shape feature F11

[0089] The length of the first arc 211 is longer than half the circumference of the first imaginary circle VC1, which is part of the circumference of the first arc 211. Similarly, the length of the second arc 212 is longer than half the circumference of the second imaginary circle VC2, which is part of the circumference of the second arc 212. Based on the characteristics of this shape, the two arcs 211 and 212 can be made to be larger than semicircles, thus reducing the possibility of droplets falling onto the medium PM in a split state.

[0090] Shape feature F12

[0091] The connecting portion 213 has a straight shape along a first direction Dr1 that runs parallel to the first arc 211 and the second arc 212. Based on this shape, the possibility of droplets falling onto the medium PM in a split state can be further reduced.

[0092] Shape feature F13

[0093] The value R1 / D2, obtained by dividing the diameter R1 of the first imaginary circle VC1 (which includes the first arc 211 as part of the circumference) by the second distance D2 (which is the distance between the centers of the two arcs 211 and 212), is 0.775 or higher. Similarly, the value R2 / D2, obtained by dividing the diameter R2 of the second imaginary circle VC2 (which includes the second arc 212 as part of the circumference) by the second distance D2 (which is the distance between the centers of the two arcs 211 and 212), is 0.775 or higher. Based on the characteristics of this shape, the possibility of droplets falling onto the medium PM in a split state can be further reduced.

[0094] Shape characteristics F14

[0095] The diameter R1 of the first imaginary circle VC1, in which the first arc 211 is part of the circumference, divided by the width W4 in the second direction Dr2 of the connecting portion 213, yields a value of 2 or more. Similarly, the diameter R2 of the second imaginary circle VC2, in which the second arc 212 is part of the circumference, divided by the width W4 in the second direction Dr2 of the connecting portion 213, yields a value of 2 or more. Based on the characteristics of this shape, the possibility of droplets falling onto the medium PM in a split state can be further reduced. The average value of R1 / W4 is more preferably 3 or more, and particularly preferably 4 or more. Similarly, the average value of R2 / W4 is also more preferably 3 or more, and particularly preferably 4 or more.

[0096] Shape characteristics F15

[0097] The second shape 220 has a size that encloses the first shape 210. This shape characteristic further reduces the likelihood of droplets falling onto the medium PM in a split state. However, when the area of ​​the second shape 220 is too large compared to the area of ​​the first shape 210, there is a tendency for air bubbles to be drawn in when the liquid surface is pulled inwards after spraying. To prevent such air bubble ingress, it is more preferable to set the area of ​​the second shape 220 to be at least two times and no more than three times the area of ​​the first shape 210.

[0098] As described above, according to the first embodiment, since the nozzle 200 has the shape features F1 to F15 described above, the possibility of droplets falling onto the medium PM in a split state can be reduced. Furthermore, some of the shape features F1 to F15 described above can be omitted.

[0099] B. Other implementation methods

[0100] Figure 6 This is a diagram illustrating the nozzle shape according to the second embodiment. Figure 5 The only difference in the first embodiment shown is that the two ends of the connecting portion 213 are not straight but curved 213r; the rest of the structure is the same as the first embodiment. Thus, the connecting portion 213 does not necessarily have to be entirely straight; the shape of the connecting portion 213, where a portion is curved, can also be described as "a straight line along the first direction Dr1". Since this second embodiment also has the aforementioned shape features F1 to F15, it can reduce the possibility of droplets falling onto the medium PM in a splitting state, similar to the first embodiment. Furthermore, in the second embodiment, the fifth position P5 can also be set to the same position as the ninth position P9. Similarly, the sixth position P6 can also be set to the same position as the tenth position P10.

[0101] Figure 7 This diagram illustrates the nozzle shape according to the third embodiment. Figure 5The only difference in the first embodiment shown is that both sides of the connecting portion 213 are concave curves; the rest of the structure is the same as the first embodiment. More specifically, the two sides of the connecting portion 213 are curves that are closest to each other at the center in the first direction Dr1 of the connecting portion 213. Since this third embodiment also has the shape features F1 to F11 and F13 to F15 described above, the possibility of droplets falling onto the medium PM in a split state can be reduced.

[0102] Figure 8 This diagram illustrates the nozzle shape according to the fourth embodiment. Figure 5 The only difference in the first embodiment shown is that both sides of the connecting portion 213 are convex curves; the rest of the structure is the same as the first embodiment. More specifically, the two sides of the connecting portion 213 are curves that are furthest apart from each other at the center in the first direction Dr1 of the connecting portion 213. Since this fourth embodiment also has the shape features F1 to F11 and F13 to F15 described above, the possibility of droplets falling onto the medium PM in a constantly split state can be reduced.

[0103] Figure 9 This diagram illustrates the nozzle shape according to the fifth embodiment. Figure 5 The only difference in the first embodiment shown is that both sides of the connecting portion 213 are serrated folds; the rest of the structure is the same as the first embodiment. Since this fifth embodiment also has the shape features F1 to F11 and F13 to F14 described above, the possibility of droplets falling onto the medium PM in a split state can be reduced.

[0104] Figure 10 This is a magnified view showing the cross-sectional shape of the nozzle according to the sixth embodiment. Figure 4 The difference in the first embodiment shown is that the positions of the first portion 210 and the second portion 220 along the injection direction Z are different from those of the second portion 220. Figure 4 On the contrary. That is, in Figure 10 In the middle, the second part 220 has a nozzle opening 216, and the first part 210 is located on the upstream side compared to the second part 220.

[0105] Figure 11 To indicate Figure 10 A diagram showing the nozzle shape of the sixth embodiment viewed from the XI-XI direction. (Compared to...) Figure 5 The only difference between the first embodiment shown is that, and Figure 5 Compared to the smaller size of the second shape 220, the first shape 210 is smaller. Figure 5The same applies. Although the second shape 220 is not the same size as the first shape 210, it has an oval shape. In other words, in this sixth embodiment, when a specific position downstream of the first position Pz1 in the jet direction Z within the nozzle 200 is designated as the second position Pz2, the second shape 220 at the second position Pz2 of the nozzle 200 has an oval shape with the first direction Dr1 as the long side direction. Even in this manner, the possibility of droplets falling onto the medium PM in a split state can be reduced to some extent. However, the positional relationship between the first shape 210 and the second shape 220 in the jet direction Z is more preferred than that described in the first embodiment.

[0106] Figure 12 This is a diagram showing the nozzle shape according to the seventh embodiment. Additionally, in Figure 12 The illustration of the second shape 220 is omitted, and only the first shape 210 is depicted. Figure 5 The only difference in the first embodiment shown is that the lengths of the two arcs 211 and 212 are each less than half the circumference. In other words, there are no positions in the first shape 210 of this embodiment corresponding to the fifth position P5 and the sixth position P6 as shown in the first embodiment. Although the seventh embodiment does not have the shape features F2 and F11 described above, it has other shape features F1, F3 to F10, and F12 to F15. Therefore, it is expected that the possibility of droplets falling onto the medium PM in a split state can be reduced to some extent. However, the lengths of the two arcs 211 and 212 are preferably longer than half the circumference. In addition, in this embodiment, the first distance D1 between the third position P3 and the fourth position P4 and the second distance D2 between the center C1 of the first imaginary circle VC1, which is part of the circumference of the first arc 211, and the center C2 of the second imaginary circle VC2, which is part of the circumference of the second arc 212, are different. Specifically, the first distance D1 is longer than the second distance D2, and coincides with the entire width of the connecting portion 213 in the first direction Dr1, i.e., the seventh width W7. Furthermore, in this embodiment, the seventh position P7 can also be set to the same position as the third position P3, and the eighth position P8 can also be set to the same position as the fourth position P4.

[0107] Figure 13 This diagram illustrates the nozzle shape according to the eighth embodiment. In the eighth embodiment, arcs 211 and 212 are not perfect circles, but ellipses; the other shapes are similar to... Figure 5The first embodiment shown is largely the same. However, the diameters of the imaginary circles VC1 and VC2 in the first direction Dr1 and the second direction Dr2 are different, with the diameter in the first direction Dr1 being longer. Although this eighth embodiment does not possess the aforementioned shape features F4 and F10, it does possess other shape features F1-F3, F5-F9, and F11-F15. Therefore, it is expected that the possibility of droplets falling onto the medium PM in a fragmented state can be reduced to some extent.

[0108] • Variation Example 1

[0109] While the various embodiments described above exemplify a serial liquid injection device 400 in which the carriage 434 holding the liquid injection head 100 reciprocates, this disclosure can also be applied to a row-type liquid injection device in which multiple nozzles 200 are distributed across the entire width of the medium PM. That is, the carriage holding the liquid injection head 100 is not limited to a serial carriage, but can also be a structure that supports the liquid injection head 100 in a row. In this case, for example, multiple liquid injection heads 100 are arranged side by side in the width direction of the medium PM, and these multiple liquid injection heads 100 are held together on one carriage.

[0110] • Variation Example 2

[0111] The liquid jetting apparatus illustrated above can be used not only in equipment specifically designed for printing, but also in various other devices such as fax machines and copiers. However, the applications of the liquid jetting apparatus are not limited to printing. For example, a liquid jetting apparatus for jetting solutions of color materials is used as an apparatus for manufacturing color filters for display devices such as liquid crystal display panels. Furthermore, a liquid jetting apparatus for jetting solutions of conductive materials is used as an apparatus for manufacturing wiring or electrodes for wiring substrates. Additionally, a liquid jetting apparatus for jetting solutions of organic substances related to living organisms is used as an apparatus for manufacturing, for example, biochips.

[0112] Other methods:

[0113] This disclosure is not limited to the embodiments described above, and can be implemented in various ways without departing from its spirit. For example, this disclosure can also be implemented in the following aspects. In order to solve part or all of the problems of this disclosure, or in order to achieve part or all of the effects of this disclosure, the technical features in the above embodiments corresponding to the technical features in the various aspects described below can be appropriately replaced or combined. Furthermore, as long as the technical feature is not described as an essential feature in this specification, it can be appropriately deleted.

[0114] (1) According to a first aspect of this disclosure, a liquid injection head is provided, comprising: a drive element (301, 302) that generates pressure for injecting liquid; and a nozzle (200) for injecting liquid in a injection direction (+Z) by utilizing the pressure generated by the drive element. A specific position in the injection direction within the nozzle is designated as a first position (Pz1), the shape of the cross section at the first position of the nozzle in a direction perpendicular to the injection direction is designated as a first shape (210), a direction orthogonal to the injection direction and being the long side direction of the first shape is designated as a first direction (Dr1), a direction orthogonal to both the injection direction and the first direction is designated as a second direction (Dr2), and a straight line passing through the center (Cx) of the first shape in the first direction and extending in the second direction is designated as a first centerline (CL1). The first width (W1) of the portion of the first shape relative to the first center line on the side (-X) of the first direction, which is the widest in the second direction, is located at a third position (P3) which is a specific position in the first direction. The second width (W2) of the portion of the first shape relative to the first center line on the other side (+X) of the first direction, which is the widest in the second direction, is located at a fourth position (P4) which is a specific position in the first direction. In the first direction, the first distance (D1) between the third position and the fourth position is greater than the first width and greater than the second width.

[0115] (2) In the above liquid injection head, the following method may also be adopted, that is, the width in the second direction of the first shape at the center in the first direction, i.e., the third width (W3), is smaller than the first width and smaller than the second width; the width in the second direction of the first shape at the fifth position (P5), which is a specific position between the first center line and the third position, i.e., the fifth width (W5), is larger than the third width; and the width in the second direction of the first shape at the sixth position (P6), which is a specific position between the first center line and the fourth position, i.e., the sixth width (W6), is larger than the third width.

[0116] (3) In the above liquid injection head, the following method can also be adopted, that is, a specific position between the first center line in the first direction and the third position is set as the seventh position (P7), and a specific position between the first center line in the first direction and the fourth position is set as the eighth position (P8). The width of the first shape in the second direction, i.e. the fourth width (W4), at any position from the seventh position to the eighth position is approximately fixed.

[0117] (4) In the above liquid injection head, the following method can also be adopted, that is, a specific position between the first center line in the first direction and the third position is set as the ninth position (P9), and a specific position between the first center line in the first direction and the fourth position is set as the tenth position (P10). At the side of the first shape from the ninth position near the first direction, the distance (r1) between the first shape and the first center (C1) of the first width is approximately fixed. At the other side of the first shape from the tenth position near the first direction, the distance (r2) between the first shape and the second center (C2) of the second width is approximately fixed.

[0118] (5) In the above liquid injection head, the following method can also be adopted, that is, the value obtained by dividing the first width by the first distance is 0.775 or more.

[0119] (6) In the above liquid injection head, the following method can also be adopted, that is, the specific position between the first center line in the first direction and the third position is set as the seventh position (P7), the specific position between the first center line in the first direction and the fourth position is set as the eighth position (P8), the width of the first shape in the second direction at any position from the seventh position to the eighth position is set as the fourth width (W4), and the average value obtained by averaging the first width divided by the fourth width from the seventh position to the eighth position is 2 or more.

[0120] (7) According to a second aspect of this disclosure, a liquid injection head is provided, comprising: a drive element (301, 302) that generates pressure for injecting liquid; and a nozzle (200) for injecting liquid in a injection direction (+Z) by utilizing the pressure generated by the drive element. A specific position in the injection direction within the nozzle is designated as a first position (Pz1), and the shape of the cross-section of the nozzle at the first position in a direction perpendicular to the injection direction is designated as a first shape (210). The first shape includes a first arc (211), a second arc (212), and a connecting portion (213) connecting the first arc and the second arc. The second distance (D2) between the center (C1) of the first imaginary circle (VC1), which is a perfect circle or ellipse and is part of the first arc, and the center of the second imaginary circle (VC2), which is a perfect circle or ellipse and is part of the second arc, is greater than the diameter (R1 = W1) of the first imaginary circle measured along the first direction (Dr1) where the first arc and the second arc are parallel. The width (W3 or W4) of the connecting portion measured along the second direction (Dr2) which is orthogonal to both the first direction and the jet direction is less than the diameter of the first imaginary circle measured along the second direction.

[0121] (8) In the above liquid injection head, the following method can also be adopted, that is, the first imaginary circle and the second imaginary circle are both perfect circles.

[0122] (9) In the above liquid injection head, the following method can also be adopted, that is, the length of the first arc is longer than half the length of the circumference of the first imaginary circle, and the length of the second arc is longer than half the length of the circumference of the second imaginary circle.

[0123] (10) In the above liquid injection head, the connecting part can also be a straight line along the first direction (Dr1) where the first arc and the second arc are side by side.

[0124] (11) In the above liquid injection head, the following method can also be adopted, that is, the value obtained by dividing the diameter of the first imaginary circle by the second distance is 0.775 or more.

[0125] (12) In the above liquid injection head, the following method can also be adopted, that is, the diameter of the first imaginary circle is divided by the width (W4) of the connecting part in the second direction to obtain a value of 2 or more.

[0126] (13) In the above liquid injection head, the following method can also be adopted, that is, a specific position in the nozzle that is upstream of the injection direction compared with the first position is set as the second position (Pz2), and the shape of the cross section at the second position of the nozzle in the direction perpendicular to the injection direction is a second shape (220) that is different from the first shape, and the second shape is the size that encloses the first shape.

[0127] (14) In the above liquid injection head, the following method can also be adopted, that is, a specific position in the nozzle that is downstream of the injection direction compared with the first position is set as the second position (Pz2), and the shape of the cross section at the second position of the nozzle in the direction perpendicular to the injection direction is a second shape (220) that is different from the first shape. The second shape is an oval shape with the first direction as the long side direction.

[0128] (15) The liquid injection head described above may also be provided with: a first pressure chamber (131); a second pressure chamber (132); a connecting channel (134) extending along the first direction and connecting the first pressure chamber and the second pressure chamber, the nozzle being disposed in the middle of the connecting channel, and the driving element including a first driving element (301) corresponding to the first pressure chamber and a second driving element (302) corresponding to the second pressure chamber.

[0129] (16) In the above liquid injection head, the following method can also be adopted, that is, the viscosity of the liquid supplied to the nozzle at 25°C is less than 20 mPa·s.

[0130] (17) The third aspect of this disclosure includes: the liquid injection head (100) described above; and a liquid storage section (420) that stores the liquid supplied to the liquid injection head.

[0131] This disclosure can also be implemented by various means other than liquid injection heads and liquid injection devices. For example, it can be implemented by a method for manufacturing liquid injection heads and liquid injection devices, or a method for controlling liquid injection heads and liquid injection devices, a computer program for implementing the control method, or a non-transitory recording medium on which the computer program is recorded.

[0132] Symbol Explanation

[0133] 100…Liquid injection head; 110…First common liquid chamber; 120…Second common liquid chamber; 130…Connecting flow channel; 131…First pressure chamber; 132…Second pressure chamber; 134…Connecting flow channel; 140…Connecting plate; 150…Sealing membrane; 160…Flow channel base plate; 170…Circulating flow channel; 180…Circulating mechanism; 200…Nozzle; 210…First part (first outline); 211…First arc; 212…Second arc; 213…Connecting part; 213 r…curve; 216…nozzle opening; 220…second part (second shape); 240…nozzle plate; 301…first drive element; 302…second drive element; 310…vibrating plate; 400…liquid injection device; 420…liquid reservoir; 430…moving mechanism; 432…belt; 434…slide carriage; 440…conveying mechanism; 450…control unit; D1…first distance; D2…second distance; VC1…first imaginary circle; VC2…second imaginary circle.

Claims

1. A liquid injection head, characterized in that, have: First pressure chamber; Second pressure chamber; A first driving element, corresponding to the first pressure chamber, generates pressure for spraying liquid; A second drive element, corresponding to the second pressure chamber, generates pressure for jetting liquid; A connecting channel extends along a first direction and connects the first pressure chamber with the second pressure chamber. A nozzle, positioned midway through the communicating flow channel, is used to eject liquid in the injection direction by utilizing the pressure generated by the first and second driving elements. The position within the nozzle in the spray direction is defined as the first position, and the first position is the position of the top end of the nozzle on the spray direction side. The shape of the cross-section at the first position of the nozzle in the direction perpendicular to the spray direction is defined as the first shape. The direction orthogonal to the spray direction and forming the long side direction of the first shape is the first direction. The direction orthogonal to both the jet direction and the first direction is defined as the second direction. The straight line that passes through the center of the first shape in the first direction and extends in the second direction is defined as the first center line. The first width, which is the largest in the second direction, of the portion of the first shape relative to the first center line on the side of the first direction, is located at the third position, which is the position in the first direction. The second width, which is the widest in the second direction, is located at the fourth position relative to the first centerline on the side opposite to the first direction. In the first direction, the first distance between the third position and the fourth position is greater than the first width and greater than the second width. The flow direction of the liquid flowing from the first pressure chamber toward the second pressure chamber in the connecting channel is the first direction.

2. The liquid injection head as described in claim 1, characterized in that, The width, i.e., the third width, at the center in the first direction of the first shape is smaller than the first width and smaller than the second width. The width of the first shape at the fifth position in the second direction, i.e., the fifth width, is greater than the third width, wherein the fifth position is the position between the first center line and the third position. The width of the first shape at the sixth position in the second direction, i.e., the sixth width, is greater than the third width, wherein the sixth position is the position between the first center line and the fourth position.

3. The liquid injection head as described in claim 1 or 2, characterized in that, The position between the first centerline in the first direction and the third position is designated as the seventh position. The position between the first centerline in the first direction and the fourth position is designated as the eighth position. The width of the first shape in the second direction, i.e. the fourth width, at any position from the seventh position to the eighth position, is within ±10% of the average value of the fourth width in the second direction over the entire range from the seventh position to the eighth position in the first direction.

4. The liquid injection head as described in claim 1, characterized in that, The position between the first centerline in the first direction and the third position is designated as the ninth position. The position between the first centerline in the first direction and the fourth position is designated as the tenth position. At the side of the first shape closest to the first direction from the ninth position, the distance between the first shape and the first center of the first width is such that the minimum value of this distance divided by the maximum value of this distance is 0.9 or greater. At the other side of the first shape from the tenth position toward the first direction, the distance between the first shape and the second center of the second width is a value greater than 0.9 obtained by dividing the minimum value of the distance by the maximum value of the distance.

5. The liquid injection head as described in claim 1, characterized in that, The value obtained by dividing the first width by the first distance is 0.775 or higher.

6. The liquid injection head as described in claim 1, characterized in that, The position between the first centerline in the first direction and the third position is designated as the seventh position. The position between the first centerline in the first direction and the fourth position is designated as the eighth position. The width of the first shape in the second direction at any position from the seventh position to the eighth position is defined as the fourth width. The average value obtained by averaging the first width divided by the fourth width from the seventh position to the eighth position is 2 or more.

7. A liquid injection head, characterized in that, have: A drive element that generates pressure for jetting liquid; A nozzle used to eject liquid in a jetting direction by utilizing the pressure generated by the drive element. The position within the nozzle in the spray direction is defined as the first position, and the first position is the position of the top end of the nozzle on the spray direction side. The shape of the cross-section at the first position of the nozzle in the direction perpendicular to the spray direction is defined as the first shape. The first shape includes a first arc, a second arc, and a connecting portion that connects the first arc and the second arc. The second distance between the center of a first imaginary circle (which is a perfect circle or ellipse and is part of the circumference of the first arc) and the center of a second imaginary circle (which is a perfect circle or ellipse and is part of the circumference of the second arc) is greater than the diameter of the first imaginary circle measured along a first direction in which the first and second arcs are parallel. By setting the width of the connecting portion, measured along a second direction orthogonal to both the first direction and the jetting direction, to be smaller than the diameter of the first imaginary circle measured along the second direction, the nozzle is configured to spray a first droplet ejected from the first arc and a second droplet ejected from the second arc in a direction that approaches each other.

8. The liquid injection head as described in claim 7, characterized in that, The first imaginary circle and the second imaginary circle are both perfect circles.

9. The liquid injection head as described in claim 7 or 8, characterized in that, The length of the first arc is greater than half the circumference of the first imaginary circle. The length of the second arc is greater than half the circumference of the second imaginary circle.

10. The liquid injection head as claimed in claim 7, characterized in that, The connecting portion is a straight line along the first direction.

11. The liquid injection head as claimed in claim 7, characterized in that, The value obtained by dividing the diameter of the first imaginary circle by the second distance is 0.775 or higher.

12. The liquid injection head as claimed in claim 7, characterized in that, The value obtained by dividing the diameter of the first imaginary circle by the width of the connecting portion in the second direction is 2 or more.

13. The liquid injection head as described in claim 1 or 7, characterized in that, The position within the nozzle that is upstream of the spray direction compared to the first position is designated as the second position. The cross-sectional shape of the nozzle at the second position, in the direction perpendicular to the spray direction, is a second shape that differs from the first shape. The second shape is the size that encloses the first shape.

14. A liquid injection head, characterized in that, have: A drive element that generates pressure for jetting liquid; A nozzle used to eject liquid in a jetting direction by utilizing the pressure generated by the drive element. The position of the top of the nozzle on the spray direction side is set as the second position. The position within the nozzle that is upstream of the spray direction compared to the second position is designated as the first position. The shape of the cross-section at the first position of the nozzle in the direction perpendicular to the spray direction is defined as the first shape. The direction orthogonal to the spray direction and forming the long side direction of the first shape is defined as the first direction. The direction orthogonal to both the jet direction and the first direction is defined as the second direction. The straight line that passes through the center of the first shape in the first direction and extends in the second direction is defined as the first center line. The first width, which is the largest in the second direction, of the portion of the first shape relative to the first center line on the side of the first direction, is located at the third position, which is the position in the first direction. The second width, which is the widest in the second direction, is located at the fourth position relative to the first centerline on the side opposite to the first direction. In the first direction, the first distance between the third position and the fourth position is greater than the first width and greater than the second width. The cross-sectional shape of the nozzle at the second position, in the direction perpendicular to the spray direction, is a second shape that differs from the first shape. The second shape is an oblong, elliptical, or oval shape with the first direction as its long side.

15. A liquid injection head, characterized in that, have: A drive element that generates pressure for jetting liquid; A nozzle used to eject liquid in a jetting direction by utilizing the pressure generated by the drive element. The position of the top of the nozzle on the spray direction side is set as the second position. The position within the nozzle that is upstream of the spray direction compared to the second position is designated as the first position. The shape of the cross-section at the first position of the nozzle in the direction perpendicular to the spray direction is defined as the first shape. The first shape includes a first arc, a second arc, and a connecting portion that connects the first arc and the second arc. The second distance between the center of a first imaginary circle (which is a perfect circle or ellipse and is part of the circumference of the first arc) and the center of a second imaginary circle (which is a perfect circle or ellipse and is part of the circumference of the second arc) is greater than the diameter of the first imaginary circle measured along a first direction in which the first and second arcs are parallel. The width of the connecting portion, measured along a second direction orthogonal to both the first direction and the jet direction, is smaller than the diameter of the first imaginary circle measured along the second direction. The cross-sectional shape of the nozzle at the second position, in the direction perpendicular to the spray direction, is a second shape that differs from the first shape. The second shape is an oblong, elliptical, or oval shape with the first direction as its long side.

16. A liquid injection head, characterized in that, have: First pressure chamber; Second pressure chamber; A first driving element, corresponding to the first pressure chamber, generates pressure for spraying liquid; A second drive element, corresponding to the second pressure chamber, generates pressure for jetting liquid; A connecting channel extends along a first direction and connects the first pressure chamber with the second pressure chamber; A nozzle, positioned midway through the communicating flow channel, is used to eject liquid in the injection direction by utilizing the pressure generated by the first and second driving elements. The position within the nozzle in the spray direction is defined as the first position, and the first position is the position of the top end of the nozzle on the spray direction side. The shape of the cross-section at the first position of the nozzle in the direction perpendicular to the spray direction is defined as the first shape. The first shape includes a first arc, a second arc, and a connecting portion that connects the first arc and the second arc. The second distance between the center of a first imaginary circle (which is a perfect circle or ellipse and is part of the circumference of the first arc) and the center of a second imaginary circle (which is a perfect circle or ellipse and is part of the circumference of the second arc) is greater than the diameter of the first imaginary circle measured along a first direction in which the first and second arcs are parallel. The width of the connecting portion, measured along a second direction orthogonal to both the first direction and the jet direction, is smaller than the diameter of the first imaginary circle measured along the second direction. The flow direction of the liquid flowing from the first pressure chamber toward the second pressure chamber in the connecting channel is the first direction.

17. The liquid injection head according to any one of claims 1, 7, 14 to 16, characterized in that, The liquid supplied to the nozzle has a viscosity of less than 20 mPa•s at 25°C.

18. A liquid injection device, characterized in that, have; The liquid injection head according to any one of claims 1 to 17; A liquid storage section for storing the liquid supplied to the liquid jet head.

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